In the past, avionics engineers have frequently been called upon to mount numerous components or LRM's, in a single rack of an avionics system. Typically these holddowns did not hold the LRM's sufficiently secure to prevent relative notion between the mated connectors located in the rear of the LRM and in the mating cabinet. As demands for improved connector electrical performance increased, this relative motion, and the related degradation in electrical performance, became an increasingly important problem. There have been several previous unsuccessful attempts to overcome these problems. One of the methods of mounting LRM's in a single rack that was proposed in the past, is to use a single long screw bolt disposed through the center of the LRM. Another approach was to use a single screw bolt at the bottom of the LRM. Yet another approach for avionics mounting systems was to include two drive screw bolts through the LRM, one at the top and the other at the bottom, with a chain drive mechanism connecting the two screw bolts.
While these approaches have enjoyed some appeal in the past, they do have several serious drawbacks. First of all, the approach of using a screw through the center of the LRM takes up valuable space inside the LRM and requires the designers of the LRM to literally design the internal parts of the LRM around the center bolt. Furthermore this design has limited ability in providing front-end support of the LRM. The second approach of using a single screw bolt at the bottom of the LRM has a disadvantage in that it does not provide for maintaining sufficient force at the side of the LRM opposite from the only screw bolt. The approach which used two drive screws and a chain-drive mechanism with a slip clutch has disadvantages in the complex nature of the interworkings between the sprockets, chain and slip clutch.
Consequently, there exists a need for improvement in systems for mounting LRM's in avionics systems.